The present invention relates generally to medical devices, and more particularly to an annuloplasty ring useable for surgical correction of certain disorders of the atrioventricular (i.e., mitral and tricuspid) valves of the human heart.
In many patients who suffer from disfunction of the mitral and/or tricuspid valves(s) of the heart, surgical repair of the valve (i.e., xe2x80x9cvalvuloplastyxe2x80x9d) is a desirable alternative to valve replacement. One specific group of patients who are typically candidates for such surgery is children who suffer from congenital valvular anomaly (CVA) or rheumatic valvular disease (RVD).
Remodeling of the valve annulus (i.e., xe2x80x9cannuloplastyxe2x80x9d) is central to many reconstructive valvuloplasty procedures. In 1968, Dr. Alain Carpentier published studies which demonstrated that such remodeling of the valve annulus might be accomplished by implantation of a prosthetic ring (i.e. xe2x80x9cannuloplasty ringxe2x80x9d) to stabilize the annulus and to correct or prevent valvular insufficiency that may result from defect disfunction of the valve annulus. Annuloplasty rings are typically constructed of a resilient core covered with a fabric sewing ring. Annuloplasty procedures are performed not only to repair damaged or diseased annuli, but also in conjunction with other procedures, such as leaflet repair.
The prior art has included numerous annuloplasty rings, such as those described in U.S. Pat. Nos.: 4,042,979 (Angell), U.S. Pat. No. 4,290,151 (Massana); U.S. Pat. No. 4,489,446 (Reed); U.S. Pat. No. 4,602,911 (Ahmadi et al.); U.S. Pat. No. 5,061,277 (Carpentier et al.); and U.S. Pat. No. 5,201,880 (Wright et al.), as well as International Patent Publication WO 91/17721 and Foreign Patent Publication SU 197710.
One problem associated with the annuloplasty rings of the prior art is that when such annuloplasty rings are implanted into children or adolescents (such as pediatric patients with CVA or RVD) the subsequent growth of the patient may render the annuloplasty ring too small for its intended function, thus abnormally constricting the annulus. The mitral annulus, for example, typically grows from about 16 mm across its longest dimension, to about 34 mm in adults. Follow-up surgery would be necessary to replace the originally implanted annuloplasty ring with a larger ring suitable for the then-current size of the patient. However, the tissue of the heart valve annulus grows into the fabric suture ring by design so that the ring is soon embedded in living tissue, making such replacement surgery problematic. Therefore, reconstructive valvuloplasty surgery on younger patients is often done using just sutures to bolster the annulus, or in conjunction with pieces of woven polyester or other biocompatible material. Such repairs may restore the normal geometry of the annulus, but are unlikely to maintain that geometry without additional structural support, and therefore are associated with less reliable and durable results.
Although some of the annuloplasty rings of the prior art have incorporated means for adjusting the size of the ring at the time of implantation, the inventors are aware of no prior art annuloplasty ring constructed and equipped for post-implantation size adjustment, in situ, to accommodate changes in annular size due to growth of the patient.
The present invention provides an expandable annuloplasty ring for implantation in a heart valve annulus. Desirably, the ring is adapted to expand upon natural growth of the patient""s annulus, or upon application of a dilatation force surgically applied. A fabric covering is preferably radially expandable.
In accordance with the invention, the annuloplasty ring may be formed of a non-elastic polymer or other distensible material, such as polyacetyl, which will remain distended after the application of natural growth forces or outward dilatory pressure has been terminated. Desirably, the non-elastic ring includes a discontinuity positioned in a more stable area of lower growth such as in the straight side of a D-shaped ring that is positioned on the anterior side of the mitral valve annulus.
In a preferred method of repairing a heart valve annulus, an adjustable annuloplasty ring is implanted in the annulus. The size of the implanted annuloplasty ring may be adjusted by inserting a dilation apparatus into the valve in which the annuloplasty ring is implanted and distending the annuloplasty ring to a larger annular size. The step of adjusting may include advancing a catheter transluminally through the vasculature to a point where the distal end of the catheter is positioned adjacent the valve wherein the annuloplasty ring is implanted, and subsequently advancing said dilation apparatus through said catheter and into its desired position within the valve for subsequent dilation of the annuloplasty ring. Alternatively, the ring may be capable of expanding upon growth of the annulus. Expansion of the implanted self-expanding annuloplasty ring may still be assisted by inserting a dilation apparatus into the valve in which the annuloplasty ring is implanted and distending the annuloplasty ring to a larger annular size.
In accordance with a further aspect of the present invention, a distensible annuloplasty ring is provided which may expand, in situ, spontaneously from the forces exerted by growth of the heart, or by way of transvascularly and/or transseptally positionable valve expansion apparatus. When dilatory or outward pressure is exerted against the ring, as may be accomplished spontaneously from the forces exerted by growth of the heart, or by way of a radially expandable member (e.g., a balloon or expandable wire cage) introduced within the annulus of the remodeled valve, such pressure will expand the ring to a larger annular size.
Still further in accordance with the invention, there is provided a method for performing remodeling annuloplasty of an atrioventricular valve, with, if necessary, a subsequent transluminal and/or transeptal procedure for enlargement of the annuloplasty ring to accommodate growth of the patient.
Further objects and advantages of the invention will become apparent to those skilled in the art, upon reading of the following Detailed Description of the Preferred Embodiments and consideration of the accompanying drawings.